1. Field of the Invention
The present invention relates to a treatment sheath for endoscopes blood vessel harvesting, by which subcutaneous blood vessels such as a great saphenous vein are harvested in an endoscopic manner.
2. Description of the Related Art
A cannula and surgical method for use in drawing and harvesting subcutaneous blood vessels such as a great saphenous vein in an endoscopic manner are known, for example, by PCT/US99/31242 and Jpn. Pat. Appln. KOKAI Publication No. 2000-37389.
The cannula is a straight tubular member which has a device inserting path inside, and includes an operation portion in a proximal end. Through the device inserting path of the cannula, from an operation portion side, a traction portion, rigid endoscope, and incision forceps are detachably inserted. The traction portion includes a loop portion projecting from a tip end of the cannula and having an angle with respect to an axial direction of the cannula in a distal end.
When the cannula is used to harvest the subcutaneous blood vessels such as the great saphenous vein in the endoscopic manner, the following surgical method is used. That is, as shown in FIG. 37, a reference numeral 100 denotes a leg. To harvest a harvesting object blood vessel (hereinafter referred to as the blood vessel) C such as the great saphenous vein which extends over the whole length to an ankle B from an upper part of an inguinal portion A of a femoral region, a cut skin portion E1, E2, or E3 is made by a scalpel, for example, in any one portion of an upper portion of the inguinal portion A, knee D, and ankle B immediately above the blood vessel C.
Subsequently, the blood vessel C is exposed in a position of each cut skin portion E1, E2 or E3 by a dissector. Furthermore, a tissue right above the blood vessel C is exfoliated by the similar dissector with respect to a distance from each cut skin portion E1, E2 or E3, which can be observed with the naked eye.
FIG. 38 is a sectional view taken along line 38-38 of FIG. 37, reference numeral 101 denotes a scurf skin, 102 denotes a subcutaneous tissue, 103 denotes a connective tissue on the blood vessel, and the blood vessel C exists under the connective tissue on the blood vessel 103. First, a cannula including a conical chip on the tip end of the cannula is used as the dissector to strip the blood vessel C and peripheral tissue and to form a cavity G. Here, the harvesting of the blood vessel C extending toward the inguinal portion A through the cut skin portion E2 of the knee D will be described. The harvesting comprises: removing the conical chip from the cannula tip end; inserting the cannula into the cavity G from the cut skin portion E2; and inserting the cannula along the upper portion of the blood vessel C during observation with the rigid endoscope.
In the process of the inserting of the cannula into the cavity G, an operation comprises: operating the operation portion in the proximal end of the cannula to move the traction portion forwards/backwards; holding the blood vessel C with the loop portion in the distal end to strip the vessel from the subcutaneous tissue 102 and connective tissue on the blood vessel 103; and cutting a plurality of side branches F branched from the middle of the blood vessel C by the incision forceps. This operation is repeated to harvest the blood vessel C between the cut skin portion E2 and inguinal portion A.
Additionally, the above-described PCT/US99/31242 and Jpn. Pat. Appln. KOKAI Publication No. 2000-37389 includes a structure in which the traction portion, rigid endoscope, and incision forceps are inserted through the device inserting path of the cannula so as to be attachable/detachable. However, the traction portion is disposed in an axial center portion of the cannula, and the rigid endoscope and incision forceps are disposed in eccentric positions in the outer peripheral portion of the cannula.
Therefore, the cannula is pushed forwards into a narrow cavity, the outer peripheral portion of the cannula contacts the tissue in the cavity, therefore mucosa, blood, and subcutaneous fat easily stick to an objective lens surface of the rigid endoscope disposed in the outer peripheral portion of the cannula in an eccentric manner, and there is a problem that a view field of the rigid endoscope is obstructed.
Moreover, when the harvested blood vessel is used as a bypass of the heart, all the side branches F branched from the middle of the blood vessel C are bound with ligatures, and therefore a long side branch F is required for securing a knot margin. Furthermore, when the side branches F are cut, a safety margin needs to be secured so as to prevent the blood vessel C as a main vessel from being damaged.
However, as in the above-described PCT/US99/31242 and Jpn. Pat. Appln. KOKAI Publication No. 2000-37389, when the traction portion is disposed in the axial center portion of the cannula, the tip end of the traction portion needs to include a curved structure in order to detach the blood vessel C from the incision forceps. When the loop portion is disposed in the curved tip end of the traction portion, and when the cannula is moved forwards/backwards, the blood vessel C may be sometimes caught by the loop portion. Furthermore, the traction portion extending from the axial center of the cannula largely enters the endoscope view field, and therefore there is a problem that the endoscope view field is obstructed.
Moreover, the PCT/US99/31242 and Jpn. Pat. Appln. KOKAI Publication No. 2000-37389 include the structure in which the traction portion, rigid endoscope, and incision forceps are inserted through the device inserting path of the cannula so as to be attachable/detachable, and therefore the structure of the operation portion is complicated. Moreover, an operator holds the operation portion of the cannula with one hand, and operates the traction portion forwards/backwards to hold the blood vessel C with the other hand. In this state, the operator changes the traction portion to the incision forceps in the hand, and operates the incision forceps to cut the side branches F. Therefore, there is a problem that the operator can only operate the cannula with both hands.